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28 The Perception of Time in Hypnosis Peter Naish 28.1 Introduction It would be understandable for a reader to wonder why, out of all the situations that might reasonably have an influence upon time perception, something as esoteric as hypnosis has been chosen as a topic. As might be guessed, it is because hypnosis has a rather special impact upon temporal judgment, and trying to discover why has the potential to add to our understanding of both hypnosis and time perception. It has been recognized for a long time (Bowers & Brenneman, 1979) that when people are roused from a session of hypnosis and asked how long they believe it lasted, they are liable to produce a considerable underestimate. It is not unusual for the participant to suggest as little as half the true duration. In terms of an inner clock, it is as if the system has slowed; in terms of the widely cited scalar expectancy theory (Gibbon, 1977), possible explanations would include the tick rate of the pacemaker being reduced by hypnosis or ticks being missed from the accumulator. From time to time in this account, it will be necessary to describe something of the nature of hypnosis. An important observation is that people vary in their responsiveness to the procedure. In research settings, scales of hypnotic susceptibility are used; they typically comprise of the order of a dozen test suggestions, ranging from motor effects (e.g., “Your arm is getting light and will float up”) to sensory experiences (e.g., “You will begin to hear music playing”). The distribution of susceptibility, i.e., responsiveness to suggestion , is approximately normal, with only a few people able to pass every item in the test, but equally few passing none. If hypnosis were responsible for causing time distortion, it would be reasonable to suppose that participants with higher susceptibility would experience more distortion. Although a few early reports suggested that this was indeed the case, subsequent research was unable to find a simple correlation (see St. Jean et al., 1994 for a review). In the period of St. Jean’s studies, hypnosis was regarded with a growing sense of realism, if not complete skepticism. It was very clear that none of the earlier, almost magical beliefs about hypnosis was tenable, and it was equally apparent that all the items in the 622 Peter Naish susceptibility tests could either be faked (lifting a “light” arm) or were unverifiable (hearing music). Some researchers (e.g., Wagstaff, 1981) were inclined to believe that much so-called hypnotic behavior represented simple compliance: people acted out what was expected of them by the experimenter. A somewhat less skeptical approach (e.g., Spanos, 1991) proposed that a willingness to “go along with” the suggestions enabled some people to convince themselves that the effects they achieved were occurring automatically. Crucially, these accounts were ascribed to simple psychological processes, so the notion that hypnosis represented a distinct state of consciousness, different from normal, appeared to be unsupported . If this was correct and hypnosis did not produce any significant, distinctive changes in the brain, it would seem to follow that it was unlikely to have any consistent impact upon timing: if any effect were observed at all, it must come about through some side effect of the situation. 28.2 Things That Do Not Cause Time Distortion Although not an essential ingredient of a hypnotic induction, it is traditional to begin a session with suggestions for relaxation. It is conceivable that the resultant sense of heaviness reported by many people could be accompanied by a slowing of neural activity, including that which underpins the clock. Fatigue is known to affect neural response times, and this has been demonstrated in air traffic controllers, whose critical flicker fusion frequency (CFF) is depressed at the end of a shift. Conversely, CFF is raised by the consumption of stimulant drinks (Hindmarch et al., 1998). The CFF is measured using a flashing light and adjusting the frequency to determine the transition point at which the flashing appears to change to continuous illumination. This procedure has been used with people both in and out of hypnosis, and no shift in CFF was found (Naish, 2001). It would seem that a fatigue-like effect is unlikely to be the time-distorting element of hypnosis. Following hypnosis, some participants may exhibit a degree of amnesia for the events that took place, or for the suggestions that were given during the session (especially if these included suggestions for...

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